anti-Necropolis faction

Another hero will rush to mass produce units and cast Divine Intervention. And by the time the undead finally move, half of their army will be gone.

I might shock you, but Divine Intervention is only effective against a stack that has already killed a few units, so casting it on the first turn might not be very effective, and it won't bring any good.

It's very important, as the upgrade helps a lot in fighting mage heroes, activating the Goblin Shaman's ability, which significantly weakens the spell of the hero or unit that this ability is activated on.

Yeah, if there are more than five hundred of them. In smaller numbers, the chance of them doing any damage is very, very small.
As an anti-undead strategy, maybe the Academy would work... Gargoyles and golems against vampires, and so on. Miniatures will give the creatures the first turn, plus flexibility in magic. You can learn light, summoning, and chaos... take your pick. And as a hero... hmm... Jaleel) and there will be a good chance of not getting hit by a spell. Besides, considering the relative weakness of most Academy creatures, if the creatures do get hit by Berserk, the losses won't be as great as if they were Hydras, Executioners, or Tany, or Onti, who can also bind... or... or...